1. No, it is certainly not fine to stay with a married woman but the persons not connected to him at that time have no locus standii to question the legality of his said act at that time,
2. You were not connected to him at that time for which you can not lodge any complaint now for his said past act,
3. However, you can certainly agitate for his taking your consent for marriage with him by suppressing the above vital fact from you since had it been made known to you, you would have refused to marry him,
4. Based on the above ground, you can file a petition praying for annulment of your marriage.